ski

In that sense, yes. One can also install headers, which will reduce efficiency losses by increasing the engine's exhaust scavenging efficiency. Or FI, which will increase the engine's volumetric efficiency.
However, your original comment stated "plus other "drag" on the engine such as the water pump, alternator, etc.", which implied the stock water pump, alternator, and other stock belt driven accessories.

JIM5.0

+1

And in this line of thought, aluminum drive shafts will do absolutely nothing to increase crank HP.

Well, kind of. If you look at it in terms of Newton's 3rd law (well, as it is translated into torque): For a torque exerted on the flywheel by the crankshaft, the drive shaft will exert an equal and opposite torque onto that flywheel.

But do note that the counter torque on the flywheel does not reduce crankshaft BHP. It only represents the total torque load which equals the sum of all the forces acting on the car and also the frictional forces in the drivetrain downstream of the flywheel. And of course, it is the net linear force where the tire patch hits the asphalt that determine if the car will actually go anywhere.

The benefits of the lighter aluminum drive shaft are you car could shed some total weight; not much, maybe 20 lbf? I am not sure exactly how much lighter they are.
As for rotational mass, it all depends on the diameter and where on that diameter the average mass of the shaft lies. What I am trying to say is it is very possible that a much lighter shaft can still be just as hard to accelerate into a rotation. For example, if you have a heavier steel shaft but the diameter is small, and you have a lighter alum shaft but the diameter is sufficiently larger, the heavier but smaller diameter steel shaft could actually be easier to accelerate into a rotation.

CandyRedGT

I have a Dyno Tech shaft in my car and love it.

ski

Yep.
And the quicker an engine can spin up the drivetrain's rotating mass, the quicker it gets into the meat of its maximum torque range for max acceleration.

JIM5.0

Oh yeah. Getting to where the meat of your torque curve quickly and staying at and above that bandwidth of your torque curve is what will get you your best ETs.

I often hear some incorrectly call this meaty part of the torque curve the "torque band." The entire torque curve is the band (short for bandwidth). What they should do is define where they get the best torque, for example, from 3000-7500 RPM. Simply saying "torque band" is too broad and by default means the entire torque curve, not just where the best part of the torque curve resides.

AllGT

The aluminum drive shaft mod is absolutely invaluable. The engine revs much much faster and it makes it soo much easier to jump off the green light line especially with the gas pedal lag that is inherent in out S197's. It is definitely a fun mod. Money well spent. No more embarrassing clunking when shifting either.

Esch

Just curious what kind of DS you've got.

JIM5.0

I don't know about AllGT, but I kind of have my eye on http://www.axle-exchange.com/.
In their ads, they advertise that the yokes on this thing will not fail until 4,000 ft-lbf torque.
I have no idea what torque this shaft is rated at, that was no advertised.
I also don't know what the rotational inertia is on his thing, that was not advertised either.

JimC

You should check out the Shaftmasters - I don't think you will find a better price or better customer service, and it is a quality piece. They offer a direct bolt in, no flange change or adapters needed.

http://www.shaftmasters.com/mustang-...iveshafts.html

baddog671

That's what I have, the 3.5" GT version. Definitly a winner